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HES - Heart Energy Signature

Typical clinical complaint with the spectrogram is that it can not separate S1 from the
murmur or allow to separate S2 clearly or to see A2 and P2 components clearly. Same
goes for S3 and S4 sounds. (follow this l
ink for further details)

Heart Energy Signature Method Spectrogram developed by Biosignetics is shown below:

                         S1           Murmur              S2(sp)         S3                                 S1       murmur                S2

                          Murmur                                                   Split S2                         S3      

Further detail shows first heart beat without S1 - murmur, S2 and S3. Note clear separation of Murmur, A2
and P2 components is S2 and S3 is clearly visible.

Also S1 shows clear separation of mitral and tricuspid components on the Energy Power vs. Time Plot

                (1)    (2) 

and S2 also shows clear A2 and P2 on the same plot

               A2        P2  components                 S3 sound 


Heart Energy Signature Aortic Insufficiency Image Album

Here we illustrate an example of detailed image post-processing for the case of aortic insufficiency. All images were developed using Bsignal - Heart Energy Signature Software

Original Heart Sound Data was obtained from the publicly available Heart Sound Data
on the Class 2000 page of the Baylor College of Medicine in Houston.


Process Flow. We first acquire the signal by opening corresponding wave file recording.
Software will automatically recognize wave file recording frequency for proper temporal
and frequency processing.

Phonocardiograph Output

Four Heart Beats

AI - Three Heart Beats

Phonocardiograph Output - Signal Plot showing S1 and S2

AI - S1 detail

S1 (first sound, lub- ) is much wider and consists of many harmonics, as opposite to "normal" S1

S2 -detail

S2 (second sound -dub) is smaller in comparison with normal S2

Analyzing FFT Frequency Spectrum

Spectral Phonocardiogram - shows signal frequency content. It aids in identification of the sound structure.

AI - Single Heart Beat Detail


AI - S1 signal detail

Aortic Insufficiency S1 contains considerable number of high intensity peaks

Heart Energy Signature -HES

Main HES Window - shows energy signature (upper right) and matching signal (bottom) and frequency spectrum (left).

AI - Heart Energy Signature

Unusually wide S1 energy blub is a characteristic signature of the Aortic Insufficiency. Verical scale is frequency, horizontal scale is time.

AI - Heart Energy Signature

Same as on the previous picture. Scale Intensity adjusted to show higher energy detail. We can see that S1 has much higher energy than S2 and also at higher frequency.

HES - Integral Power and Energy Density Spectrum

This is quantitative characteristic of the heart energy signature. Allows easy signal segmentation and qantification.

HES - Instant Power and Energy Density Spectrum

Flying Crossbar allows operator to select specific frequency to extract the instantaneous energy from the image. Very useful for murmur characterization. Crossbar can also select specific time moment to extract energy spectrum (frequency) content to identify signal structure and components.

HES - Integral Power and Energy Density Spectrum

Frequency detail (upper left)

Heart Energy Signature

Smaller time segment was considered to save on processing time.

We can see S2 and part of S1.

Aortic Insufficiency (AI) Heart Energy Signature

HES detail emphasizing S1 structure (on the right). S1 is seen as weak blob on the left.


Same detail, showing Integral Power and Density Spectrum.

Original signal was collected at 11kHz, sample size contains 4096 data points.

AI - Frequency Spectrum

Signal was down sampled to 5.5 kHz using BSignal proprietary technology. All subsequent images were obtained for downsampled AI heart sound data.

Heart Energy Signature

Single Heart Beat

AI - Heart Energy Signature Detail

Main HES Image. Shows detailed X-ray like structure of the

Aortic Insufficiency Sound. First weak blob is S2 and second

sequence of blobs is "damaged" S1


Same as previous, but upper frequency limit is cut for better viewing

Heart Energy Signature

Upper frequency limit is cut for better viewing (vertical zoom)

AI - Heart Energy Signature

Intensity scale is lowered (see flying bar on the right) to show lower energy components better.

AI - Heart Energy Signature

Intensity scale is raised (see flying bar on the right) to show higher energy components better. Five high energy components are visible on S1. S2 is on the left, S1 is on the right.

HES - Integral Power and Density Spectrum

S1 (left) has considerably higher energy (see plot on the bottom right). Energy Density is clearly visible on the left. Unlike the spectrogram (FFT) it allows to clearly identify frequencies corresponding with the power peaks.

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Copyright: 2004-2009 BioSignetics Corporation
Last modified: 02/02/09